Various kinds of cytokines have functions such as an action of control of immune responses, an antitumor action, an antivirus action and regulation of cell proliferation/differentiation and play important roles in bio-defense reactions such as inflammatory reactions, hematopoiesis, bone metabolisms, allergic reactions and autoimmune diseases. Inflammatory cytokines such as IL-6 and TNFα are produced from various kinds of cells including immunological cells such as macrophages, and fibroblasts, vascular endothelial cells, osteoblasts and the like, and exhibit a variety of physiological activities such as induction of differentiation of B cells to antibody chain producing cells, induction of production of an acute phase protein from liver cells, and directly acting on a bone marrow-derived macrophage as precursor cells of osteoclasts to induce differentiation of the macrophage to osteoclasts. It has been found that in autoimmune diseases such as rheumatoid arthritis and Castleman disease, a large amount of IL-6 and TNFα is produced from an arthrosynovialis and a large amount of IL-6 is produced from a hypertrophic lymph node of a Castleman disease patient, and IL-6 and TNFα are considered to be a cause of these diseases (Non-Patent Document 1; Non-Patent Document 2; Non-Patent Document 3).
Hydroxamic acid derivatives, of which the usefulness as inhibitors of cytokines has been disclosed, include the following.
(1) Patent Document 1 discloses that a hydroxamic acid derivative represented by general formula (a) is an inhibitor of release of TNFα from cells and inhibits metallo-proteinase involved in disorganization.
(2) Patent Document 2 discloses that an imidazole substituted hydroxamic acid derivative represented by general formula (b) is useful as an inhibitor of a matrix degradable metallo-proteinase.
(3) Patent Document 3 discloses that a hydroxamic acid derivative represented by general formula (c) has an action of suppressing production of TNFα.
(4) Patent Document 4 discloses that a hydroxamic acid derivative represented by general formula (d) inhibits formation of human CD23 and is useful for treatment of symptoms related to overproduction of soluble CD23, such as autoimmune diseases and allergies.
(5) Patent Document 5 discloses that a hydroxamic acid derivative having a hydroxyl group at 6-position, which is represented by general formula (e), suppresses production of IL-6. Requirements for stereoisomers of the hydroxyl group at 6-position are disclosed in the specification of the patent document, and in the invention thereof, the hydroxyl group at 6-position is a necessary structural element in expression of an IL-6 production suppressing activity.
(6) Patent Document 6 discloses that a hydroxamic acid derivative represented by formula (f) suppresses production of IL-6. However, in this publication, compounds specifically described are limited to compounds of general formula (f) in which ring A and ring B are phenyl groups.
(7) Patent Document 7 discloses that an oxazole compound represented by formula (g) is effective as an anti-inflammatory agent. However, suppression of production of IL6 and/or TNFα is not described.

Patent Document 1: JP-A-9-503222
Patent Document 2: JP-A-9-509940
Patent Document 3: WO 99/61412 Pamphlet
Patent Document 4: JP-A-2000-503312
Patent Document 5: JP-A-2002-80445
Patent Document 6: WO 2002/074298 Pamphlet
Patent Document 7: U.S. Pat. No. 3,578,671
Non-Patent Document 1: Eur. J. Immunol, 18:1797-1801 (1988)
Non-Patent Document 2: Blood, 74(4):1360, (1989)
Non-Patent Document 3: Allergy/Immunology, Vol. 10, No. 9, 67-75 (2003)